Lohan, 27, took Sundance by surprise on Monday with an impromptu, 20-minute press conference about Inconceivable, a movie she will star in and produce. Plot details remain scarce: Attendees were told the project is a thriller and that Lohan's character is "a young woman on a journey to reclaim something that's she's lost," the Associated Press reports.

Sources tell PEOPLE the last-minute gathering was strange from start to finish. Just a few reporters were present, and they were forbidden from asking anything unrelated to Inconceivable – meaning questions about Lohan's personal life were off-limits.

The starlet did hint at her troubled past, calling her first-ever appearance at the Park City, Utah, festival "starting fresh," according to the AP report.

"It's therapeutic for me to throw myself into something that really excites me and something that I love to do so much," she said.

An OWN film crew captured the announcement, which should silence rumors that Lohan has flaked on an upcoming reality series chronicling her attempted comeback for Oprah's network.

Onlookers say Lohan – who completed her sixth trip to rehab in July – partied at Tao nightclub with friends the night before her big reveal but did not seem to be drinking.